Owl Pellets

Owl pellets are not scat, poop or feces of an owl, owl pellets are the parts of the owl's prey that can not be digested, those parts are put in another stomach. Six to eight hours after the owl ate its prey it will regurgitate the parts that can not be digested. When those parts are regurgitated they form the owl pellet. When I was first exploring an owl pellet, I was looking for bones and what animal they were from. The population that was found most often is probably the meadow vole. This says that an owl's main diet is the meadow vole. You won't just find one skeleton of an organism in an owl pellet you will probably find two or more skeletons in an owl pellet because the owl probably ate two organisms. The usual habitat for a meadow vole is wide open fields and forests, grass and small plants are the nearest food source for a meadow vole. An owl's habitat overlaps a meadow vole's habitat because where an owl hunts is where a meadow vole lives. If the rodent population died out owls would have to find another animal to eat, if they did not the owl population would die out too.
These are some things I want to know about owls. How can owls turn their head halfway around? Why do owls prefer to eat their food whole? Why do owls hunt at night?